Tens of thousands of patients were waiting for routine treatment at the Somerset Trust in July, figures show.
The King's Fund, a leading healthcare think tank, has said the new Prime Minister must act urgently to tackle the problems blighting the NHS as it heads into a "terrible" winter.
NHS England figures show 34,372 patients were waiting for non-urgent elective operations or treatment at Somerset NHS Foundation Trust at the end of July – down from 34,976 in June, but an increase on 30,898 in July 2021.
Of those, 1,951 (6%) had been waiting for longer than a year.
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Nationally, 6.8 million people were waiting to start treatment at the end of July – a new record.
Richard Murray, chief executive of the King's Fund, said the NHS is being "shaken to its core".
"The challenges affecting the NHS cannot be solved without addressing the systemic workforce shortages and sustained funding shortfalls in social care.
"The new PM and Secretary of State have a matter of weeks to decide what emergency short term action to take to provide at least some additional support during what promises to be a terrible winter for patients and staff.
"This could include maximising the campaigns for winter Covid boosters and flu vaccines, tackling the pensions issue driving senior staff out of the NHS, and emergency funding to boost capacity in social care."
Separate figures show 1.5 million patients in England were waiting for a key diagnostic test in July – a fall from 1.6 million in June.
At the Somerset Trust, 6,920 patients were waiting for one of 14 standard tests, such as an MRI scan, non-obstetric ultrasound or gastroscopy at this time.
Of them, 1,576 (23%) had been waiting for at least six weeks.
Responding to the latest performance figures for England as a whole, Nigel Edwards, chief executive of the Nuffield Trust, said the NHS's problems have been "years in the making".
“The new government is absolutely right to prioritise health and social care as a matter of urgency.
"Exactly how to turn this around as we go into winter will not be an easy task, but a relentless focus on the workforce, social care and hospital buildings are essential."
Other figures from NHS England show that of 91 patients urgently referred by their GP who were treated at the Somerset Trust in July, 57 were receiving cancer treatment within two months of their referral.
A month previously – when 100 patients were referred – 57 were treated within 62 days.
In July 2021, 69 patients were treated within this period, out of 95 that were referred.
New Health and Social Care Secretary and Deputy Prime Minister Thérèse Coffey said: “Clearly this level of performance is unacceptable, which is why I have set out our priorities will be ABCD: ambulances, backlogs, care and doctors and dentists.
“We know some of the backlog challenges will increase as people continue to present themselves for treatment.
"We are investing £39 billion to tackle these challenges, ensure the NHS is fully prepared for winter and fix the broken social care system.”

